I usually end up changing every year .as soon as they get their claws into you (a year's insurance) they put the price up the following year. I could be wrong here but I think it might have to do with the companies exposure to a certain category of driver on their books for a given year so Ring them all for a quote .through the years I have experienced 300 euro quote differences between the same companies within a year (for no reason) . My self I am the wrong side of 30 my insurance is a little more than 3 months tax but last year got a quote for nearly a 1000 from a company I was with a few years ago for less than half that